RWDBDataCallback and Open SQL
The data callback classes can be used with Sybase to fetch data only; inserting data is not supported. Data callbacks are useful for very large data that may not fit in memory for a single database call and are described in Section 15.3, “The Data Callback Classes,” in the DB Interface Module User’s Guide.
NOTE: The DB Access Module for Sybase does not support inserting data with the data callback classes.
When fetching data, Sybase requires that the columns bound to a data callback must be at the end of the select list. For example, if two columns of type integer and LOB are selected, the integer must come before the LOB in the select list in order to use a data callback for the LOB column.
The DB Access Module for Sybase will fetch only one row on each call to RWDBOSql::fetch().
